Jose Mourinho last night accused Manuel Pellegrini of getting his sums wrong as the row between the two over Chelsea’s spending escalated.

Pellegrini, the Manchester City manager, had said last week that Chelsea spent more than other teams – itself a response to Mourinho’s description of his Chelsea side as a “little horse” – and Mourinho insisted last night that the manager known as “the Engineer” had got his sums wrong.

“Pellegrini is a fantastic coach, and outside his football career, he’s an engineer by academic qualification,” Mourinho said yesterday, without much prompting. “I don’t think an engineer needs a calculator to know that Juan Mata’s fee of £37m and Kevin De Bruyne’s of £18m, that is £55m. Nemanja Matic cost £21m and Mohamed Salah was £11m. That’s £32m. And £55m minus £32m is £23m. So Chelsea, in this transfer window, generated £23m.”

Mourinho said that Pellegrini, with whom he has exchanged words before, must have known that he was wrong. “The message he wanted to pass out is that we are also big spenders like them, but that’s not true,” he said. “So instead of saying we’re the big spenders in the January market, it’s probably better to say we are the ones who made most money.

“I have no problems with Pellegrini. None at all. He’s doing his work. Obviously, he knows these numbers. Obviously, he knows that we had a big positive number in the transfer market. Obviously, he knows. But, obviously, he’s Man City’s manager and he’s doing his work and doing well.”

Mourinho insisted, not for the first time, that Chelsea were following Uefa’s Financial Fair Play rules more rigorously than City, admitting that they had to pull out of planned moves for Edinson Cavani and Radamel Falcao last summer because of these restrictions. “It is easy to understand that this is working with Financial Fair Play, fair Financial Fair Play. There are no arguments against that. This is what we’re doing. Others aren’t doing the same. We are building a team for the next decade, if possible. They have a team to win now.”

Despite that, Chelsea are top of the league, and victory at West Bromwich Albion tonight – when they will have Fernando Torres available again after injury – would extend Chelsea’s lead over Arsenal and City. Mourinho remains resolutely long-term in his view, though, and even said it would be “not disappointing” if Chelsea were not to regain the title this season. “I would be disappointed if my team do not keep the evolution up in every aspect of the game,” he said. “Many things can happen. I would be disappointed if my team collapses. But if we keep this level, even if we lose points and matches and don’t win the league, I wouldn’t be disappointed.”

This long-term focus means that Mourinho’s second spell at Chelsea feels different from his first, but he explained yesterday he enjoys these less immediate demands, of development and growth.

“People used to look at me as a guy who arrives at a club and attacks immediately the title. For me, this was a different profile of job: I was explained to about FFP, the style of football the team had to play, the young talented players we have here and on loan. Since day one, we are in the same direction.”

This direction is set by owner Roman Abramovich. “In this moment, I am not doing, we are doing,” Mourinho said. “It is not my philosophy, it is our philosophy. It’s not the way I want the team to play football. It’s the way we want them to play football. It’s a long-term project.”

This is a big task Mourinho has taken on – he described it as “even better and more enjoyable work” than heavy pre-FFP spending – and he admitted that he hopes this side will play more exciting football than his first Chelsea team, which won five trophies under him between 2004 and 2007, before going on to gain more after his departure.

“It’s not easy, because the other Chelsea team won a lot,” Mourinho said, when asked if this side might win more than that one. “The first objective is that this team, in terms of the quality and enthusiasm and flair of its game, is better than the previous team. The old team had qualities and personality, but the objective, because of the difference in profile, is that this team plays differently.”